Wheatstone bridge sensors generally comprise a Wheatstone bridge circuit and a high-impedance preamplifier intended to amplify the output voltage of the Wheatstone bridge, which is proportional to the supply voltage of the Wheatstone bridge.
However, the full-scale output voltage of this type of Wheatstone bridge sensor is often very low, for example from 10 to 50 mV/V. It then requires high-precision preamplification before optional digital conversions and an offset correction of the input signals of the preamplifier, that is to say the output signals of the Wheatstone bridge.
This offset may be due to mismatching of the resistors of the Wheatstone bridge or the temperature variation, and may be of the same order of magnitude, for example from 10 to 30 mV/V, as the full-scale output voltage. It is consequently necessary as far as possible to avoid amplifying this offset of output signals of the Wheatstone bridge.
Furthermore, since the typical passband of the low-speed physical values is generally from 0.1 to 100 Hz, it is desirable to have a noise level which is as low as possible.